The purpose of this Mentored Clinical Scientist Development Award (MCSDA-K08) grant is to allow the applicant to develop a research program in the study of Dysthymic Disorder in children and adolescents and to develop the skills necessary to test the hypotheses that dysthymia in this age group is: 1) a neurobiologically mediated mood disorder that is amenable to psychopharmacologic intervention, and 2) a familial disorder in which risk factors for the development of the disorder are at least in part genetically transmitted. Building on the work of several investigators who have studied chronic depression in adults, and using several of these researchers in adult psychiatry as mentors and consultants to the Principal Investigator, this program will assess the validity of the classification of Dysthymic Disorder in youth as a mood disorder using clinical samples of subjects recruited into a treatment protocol. Research studies using methodologies that have contributed to the understanding of the disorder in adult subjects are proposed. The core study to be conducted during the period of this grant is a placebo-controlled, double-blind efficacy study of Fluoxetine in the short-term treatment of Dysthymic Disorder in children and adolescents. The project described will also develop a systematic approach to studying the familiarity of chronic depression in children and adolescents, culminating in controlled family studies of pediatric-age probands in comparison to controls. Preliminary studies investigating the role of Molecular Genetics studies in contributing to the understanding of the etiology of the disorder are also proposed. The Principal Investigator, having completed clinical training and preliminary research training, is pursuing a career devoted to clinical research and, proposes to train in the research techniques of Genetic Epidemiology and Molecular Genetics as a means of enhancing its capacity to conduct future research in the chronic mood disorders of childhood and adolescence. A program of systematic didactic education, supplemented by laboratory experience, mentored supervision and independent research projects, is proposed. This MCSDA will provide the Principal Investigator with further experience in the study of chronic mood disorders in children and adolescents and foster his growth toward conducting independent clinical research.